Spaces with congruence

In this paper we consider an exchange space with congruence (P,L,≡)(P,L,≡) not assuming any further geometrical properties. If the dimension of the space is greater than 2, we show that for any line GG of a plane EE and any point x∈Gx∈G there is a unique perpendicular line through xx in EE and that any line reflection is a motion.